The need for improved means of girth adjustment in footwear is accepted in the industry as continually more offerings are being limited by market economics to single widths for each size in length. Studies, including those of the U.S. Army QMC, have shown that such single width shoes afford only an approximate fit to less than a third of the populace. Furthermore, even this third receives less than a precise fit given the normal diurnal foot girth variation that occurs with changes of fluid concentration in the extremities, usually resulting in daily girth change ranges of up to two full width increments with even wider ranges experienced when there are concurrent changes in weather, altitude or a wearer's physical condition.
The usual girth adjustment means including laces, buckles, touch fasteners and lately pressurized air and dial operated cables, not only present design limitations, but generally cannot be used in the fit-critical ball area where they would tend to inhibit the comfortable flexing of the foot in this region during the stride cycle. Furthermore, these usual girth adjustment means are not suitable for use with many shoe styles.
While this inventor's recent inventions disclose practical means of shoe girth adjustment, none of these, including U.S. Pat. Nos. 4,967,492, 5,036,604 and 5,060,402, provide such means applicable to the manufacture of unlined footwear adaptable to a wide range of conventional shoe bottom styles, including those having the usual die-cut leather or composition soles.
Past attempts to deal with shoe girth adjustment by variation of insole elements have been limited to variation in the thickness of such elements. Such approaches not only do not afford the infinite adjustability in the adjustment range preferred for optimum fit, but more importantly, present serious orthopedic risks. The latter occur when insole elements of appreciably different thicknesses are needed to provide proper fit to a wearer whose feet are of substantially different width, as not infrequently occurs. Such adjustment, given that the wearer's legs are of substantially equal length, results in one foot being higher from the walking surface than the other, often leading to serious orthopedic problems over time. Shoes having such insoles of varied thickness include those offered by Toddler's University, Inc. of Westport, Conn. and others.
Accordingly, it is one of the objects of the present invention to provide means for adjusting the fit of a shoe wherein the shoe upper is either unlined or has a conventional cement-attached lining and the shoe bottom is any conventional shoe bottom or sole assembly.
It is a further object to provide an adjustment means which does not change the actual girth of the shoe in all of the critical fitting areas thereof, including the mid-portions of the shoe known as the ball, waist and instep portions and does not change the distance of the foot from the walking surface.
It is a further object to provide an adjustment means which is substantially unobtrusive so as to not affect the appearance of the shoe.
It is still another object to provide an adjustment means which is infinitely adjustable over a designed fit range.
A further object is to provide a fit adjustment means easily adaptable for use in unlined shoes with the widest possible choice of conventional sole and/or bottom materials and where such means can be either built into the shoe at its manufacture or inserted therein after manufacture.
It is also an object to provide an adjustment means which is operably adjustable when the shoe is on the foot.